Ethylene is known to mediate a variety of growth phenomena in plants. See generally Fritz et al. U.S. Pat. No. 3,879,188. This activity is understood to be achieved through a specific ethylene receptor in plants. Many compounds other than ethylene interact with this receptor: some mimic the action of ethylene; others prevent ethylene from binding and thereby counteract its action.
Many compounds which block the action of ethylene diffuse from the binding site over a period of several hours. See E. Sisler and C. Wood, Plant Growth Reg. 7, 181-191 (1988). These compounds may be used to counteract ethylene action. A problem with such compounds, however, is that exposure must be continuous if the effect is to last for more than a few hours.
Photoaffinity labeling has been used in biological studies to label binding sites in a permanent manner: usually by generating a carbene or nitrene intermediate. Such intermediates are very reactive and react rapidly and indiscriminately with many things. A compound already bound, however, would react mostly to the binding site. In a preliminary study, it was shown that cyclopentadiene was an effective blocking agent for ethylene binding. See E. Sisler et al., Plant Growth Reg. 9, 157-164 (1990). The present invention is based on our continued investigation into compounds capable of photoaffinity labelling the ethylene receptor.